Power limiting apparatus



Oct. 27, 1936. P, N, MAR-11N 2,058,610

POWER LIMITING APPARATUS Filed July 17, 1954 5 I, 4 5 lZ '2i )2 2' f la!\Ia, 5 5 f 6 z l( TH/ l 5 XI 12 X C-1) B 7 9 I0 C B-J SZLUPLCI'JLIP IlSb- Fzg. l. Fay. 2

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UNITED `STATES iATEN-T OFFICE POWER LIMITING APPARATUS Paul N. Martin,Swissvale, Pa., assignor to The Union Switch & Signal Company,Swissvale, Pa., a corporation of Pennsylvania yApplication July 17,1934, Serial No. 735,597

12 Claims. (Cl. 246-41) My invention relates to power limiting apafterthe interval of time determined by the pickparatus, that is, toapparatus for limiting the up characteristic of relay Y, front contact BBa amount of power supplied from a source of elecwill again close toenergize relay X. This optric current to a load. Apparatus embodyingeration will be repeated as long as the car or my invention isparticularly well adapted for, train occupies any part of section 3 4.The re- 5 though in no way limited to, railway signaling sult is thatWhile the section is occupied, battery track circuits, and when so usedit provides novel 5 is periodically disconnected from the track andimproved means for insuring the release of a rails, and the periods ofdisconnection will be track relay when a car or train enters theassomuch longer than the periods of connection. It l ciated section oftrack. follows that the track relay will release with a I will describefour forms of apparatus emhigher train shunt resistance and in less timebodying my invention, and will then point out than for an ordinary trackcircuit without relays the novel features thereof in claims. X and Y,and will be less likely to pick up again In the accompanying drawing,Fig. 1 is a diwhile the section is occupied. 15 l5 agrammatic Viewshowing one form of apparatus The reason for the snubbing path aroundrelay embodying my invention. Figs. 2, 3 and 4 are X is to delay therelease of this relay for a suffidiagramrnatic views showingmodifications of the cient time to insure that the magnetic flux inapparatus shown in Fig. l and also embodying relay Y shall completelycollapse before energy my invention. is again applied to Y. Thisimproves the uni- Similar reference characters refer to similar formityof operation of the relays, and also in- 20 parts in each of the views.creases the ratio between the off and on times of Referring irst to Fig.l, the reference charbattery 5. acters I and Ia designate the trackrails of a Referring now to Fig. 2, the auxiliary relay,

stretch of railway track, which rails are divided which is heredesignated XI, comprises two opby insulated joints 2 to form atracksection 3 4. posing windings 9 and I0. Winding 9 is con- 25 A trackrelay TR is connected across the rails stantly energized from a sourceof current the at one end of this section. Located at the otherterminals of which are designated B and C. end of the section is asource of track circuit cur- Track battery 5 is connected across thetrack rails rent 5, which, as here shown, is a battery. This through acurrent-limiting impedance 6, winding 3c battery is connected across therails I and Ia I 0, and front contact II of relay XI. The parts 30through a current-limiting impedance 6, the are so adjusted thatnormally the effect of windwinding of a relay X, and a front contact 88a ing 9 predominates over the effect of winding I0 of a relay Y. Therelay Y is of the slow pickup to a suicient extent to cause irontcontact II to type, but has normal release characteristics. be closed.When a car or train enters section Relay Y is provided with a circuitwhich includes 3 4, however, the increased current which iiows 35 asource of current and a back contact I of relay through winding I0 willcause the eifects of the X. Relay X is provided with a short circuitingtwo windings to neutralize to a suihcient extent. or snubbing path whichincludes back contact to release contact II. Battery 5 will then be dis-8 8b of relay Y. connected from rail I, and contact II will again Theparts are so adjusted that when the secclose due to the absence ofcurrent in winding I0, 40 tion 3 4 is unoccupied, the current whichiiows whereupon battery 5 will again be connected with through thewinding of relay X is not suflicient rail I. This process will berepeated continuously to open back contact T, and so relay Y is then aslong as any part of the car or train occupies energized to complete theconnection of battery the section.

5 to the track rails. When a car or train enters Winding 9 may beenergized from battery 5, 45 section 3 4, however, the increased currentif desired, in which case the current through this which iiows throughthe winding of relay X is inding will vary slightly in such manner as tosufcient to effectively energize this relay, thereby tend to compensatefor changes in the voltage opening contact 'I and deenergizing relay Y.The of this battery.

consequent opening of iront contact 8 8a of relay A variable resistanceI2 may be connected in 5.0 Y will disconnect battery 5 and relay X frommultiple with winding Il) to facilitate adjusting track rail I and theclosing of back contact 8 8b the characteristics of relay XI. willcomplete the snubbing path around relay X, The apparatus shown in Fig.3, vis the same as so that after a short time interval relay X will thatshown in Fig. 2, except for the provision of again release to close itsback contact 1. Then aslow pickup relay Y which operatesin the samemanner as the corresponding relay in Fig. 1 to prolong the periodsduring which battery 5 is disconnected from the track rails. In Fig. 3battery 5 is connected across the rails through impedance 6, winding I0and front contact 8--8a of relay Y. The circuit for relay Y includesfront contact Il of relay XI. The operation of the apparatus shown inFig. 3 will be obvious from the foregoing explanation of the operationof Figs. 1 and 2.

Referring now to Fig. 4, the apparatus shown in this view is similar tothat which is shown in Fig. l, except that the snubbing path aroundrelay X is omitted, and a second slow pickup relay Z has been added toprovide for a still longer 01T period of battery 5. In Fig. 4, thebattery 5 is connected across the track rails through the winding ofrelay X and front contact 8--8 of relay Y, as in Fig. 1. Relay Y isprovided with a closing circuit which passes from terminal B, throughback contact 1 of relay X, front contact I4 of relay Z, and the windingof relay Y to terminal C. Relay Y is provided with a holding circuitwhich passes from terminal B, through back contact 1, front contactlil--lila of relay Y, and the winding of relay Y to terminal C. Relay Zis provided with a circuit which passes from terminal B, through backcontact 1, back contact I3---I3b of relay Y, and the winding of relay Zto terminal C.

Normally the parts of the apparatus shown in Fig. 4 are in theconditions in which they are shown in the drawing. When a train entersthe track section, however, relay X becomes effectively energizedbecause of the increased current drawn from battery 5. The opening ofback contact 1 of relay X opens the holding circuit for relay Y, so thatthis relay becomes deenergized thereby disconnecting battery 5 and relayX from the track rail I. Back contact 1 then closes, thereby closing thecircuit for relay Z through this contact and back contact I3--I3b ofrelay Y. After a given interval of time contact I4 of relay Z willclose, thereby completing the closing circuit for relay Y. After anotherxed interval oi' time the front contacts of relay Y will close, therebyopening the circuit for relay Z at back contact I3---I3b and closing theholding circuit for relay Y at front contact l3l3. Front contact 8--8awill, of course, reconnect battery 5 and relay X across the track rails,and the operation of the apparatus will then start again. It will beseen, therefore, that the lengths of the periods during which battery 5is disconnected from the track circuit will be longer than with theapparatus shown in Fig. l.

The present application is closely related to the copending applicationfor Railway track circuit apparatus, Serial No. 705,558, filed by L. O.Grondahl on January 6, 1934, which latter application contains claimswhich cover broadly certain features of the invention disclosed in mypresent application.

Although I have herein shown and described only a few forms of apparatusembodying my invention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a section of railway track, a source of currentconnected across the rails of said section through the winding of afirst relay and a front contact of a slow pickup relay, and a circuitfor said slow pickup relay including a contact of said rst relay, theparts being so adjusted that the first relay is effectively energizedwhen said section is occupied but not when it is unoccupied.

2. In combination, a section of railway track, a source of currentconnected across the rails of said section through the winding of a nrstrelay and a front contact of a slow pickup relay, a circuit for saidslow pickup relay including a back contact of said first relay, and asnubbing path around the winding of said first relay including a backcontact of said slow pickup relay, the parts being so adjusted that thefirst relay is effectively energized when said section is occupied butnot when it is unoccupied.

3. In combination, a section of railway track, a relay having twoopposed operating windings, means for constantly energizing one of saidwindings, a slow pickup relay, a source oi track circuit currentconnected across the rails of said section through the second winding ofsaid first relay and a front contact of said second relay, and a circuitfor said second relay including a front contact of said first relay, theparts being so adjusted that the front contact of said rst relay isnormally closed but opens due to the increase of current in said secondwinding when said section becomes occupied.

4. Incornbination, a section of railway track, a relay having twoopposed operating windings, means for constantly energizing one of saidwindings, a source of track circuit current connected across the railsof said section through the other of said windings, said relay includinga contact which is normally closed but which opens due to the increaseof current in said second winding when said section becomes occupied,and means for opening the connection of said source with one of thetrack rails when said contact is open.

5. In combination, a section of railway track, a relay having twoopposed operating windings, means for constantly energizing one of saidwindings, a source of current connected across the rails of said sectionthrough the other of said windings, and means controlled by the increaseof current in said second winding when said section becomes occupied forinterrupting the connection of said source with a rail of said track.

6. In combination, a section of railway track, a relay having twoopposed operating windings, means for constantly energizing one of saidwindings, a source of current connected across the rails of said sectionthrough the other of said windings, means controlled by the increase ofcurrent in said second winding when said section becomes occupied forinterrupting the connection of said source with a rail of said track,and an adjustable resistance connected in multiple with said secondwinding.

7. In combination, a section of railway track, a source of currentconnected across the rails of said section through the winding of afirst relay and a front contact of a slow pickup relay, a second slowpickup relay, a closing circuit for said rst slow pickup relay includinga back contact of said first relay and a front contact of said secondpickup relay, a holding circuit for said first slow pickup relayincluding a back contact of said rst relay and a front contact of saidrst pickup relay, and a circuit for said second slow pickup relayincluding a back contact of said rst relay and a back contact of saidIirst slow pickup relay, the parts being so adjusted that the iirstrelay is eiectively energized when said section is occupied but not whenit is unoccupied.

8. In combination, a load, a relay having two opposed operatingwindings, means for constant- 1y energizing one of said windings, a slowpickup relay, a source of current connected with said load through thesecond winding of said iirst relay and a front contact of said secondrelay, and a circuit for said second relay including a front contact ofsaid rst relay, the parts being so adjusted that the front contact ofsaid rst relay is normally closed but opens upon a given increase incurrent drawn from said source by said load.

9. In combination, a section of railway track, a source of track circuitcurrent connected across fthe rails of said section, a series relayhaving a winding included in the connection of said source iwith one ofthe rails, said relay normally assuming one condition when said sectionis unoccupied Iand the current in said winding is relatively low fandanother condition when the section becomes occupied by a train and thecurrent in said winding is increased, a normally energized slow actingrelay controlled by said series relay in accordance with the conditionthereof, and means controlled by said slow acting relay and eilectivewhen said series relay assumes said other condition and said section isoccupied for varying the amount of current supplied from said source tosaid section.

10. In combination, a section of railway track, a source of trackcircuit current connected across zthe rails of said section, a seriesrelay having a winding included in the connection of said source withone of the rails, said relay normally assuming one condition when saidsection is unoccupied and the current in said winding is relatively lowand another condition when the section becomes occupied by a train andthe current in said winding is increased, a slow acting relay controlledyby said series relay in accordance with the condition thereof, andmeans controlled by said slow acting relay and effective when saidseries relay assumes said other condition for interrupting the currentsupplied from said source to said section.

11. In comb-ination, a load, a source of current connected with saidload, a first relay in circuit with said load and responsive to theamount of current taken by said load, a slow acting relay controlled bysaid rst relay in such manner as to become operated when the amount ofcurrent received by said load exceeds a given value, and meanscontrolled by said slow acting relay in its operated condition forinterrupting the connection of said source with said load.

12. In combination, a load, a source of current connected across saidload through a normally closed circuit including the winding of a rstnormally deenergized relay, a normally energized slow pickup relay, acircuit for said slow pickup relay including a contact of said firstrelay, and means effective when said slow pickup relay is deenergizedfor interrupting said normally closed circuit to thereby interrupt thesupply of current from said source to said load,

PAUL N. MARTIN.

